Description:

Objective:

In tundra ecosystems where burning is rare on the modern landscape, are recent fires unique in the context of the past several millennia? Were tundra fire regimes sensitive to abrupt, large-scale climate and associated vegetation change in the past, and what does this suggest for future climate scenarios? What are the climatic conditions that exacerbate tundra burning, and how do these differ for various vegetation types?

Approach:

Paleoecological analyses of lake sediment cores will be used to reconstruct long-term climate-vegetation-fire dynamics. These analyses include macroscopic charcoal records to reconstruct fire frequency, pollen to infer vegetation change and a combination of midge assemblages and carbonate isotopes to reconstruct climate. Lakes from three tundra ecoregions in Alaska will be targeted for analyses, capturing a broad range of climate and vegetation scenarios. The long temporal span of the records (~5,000– 14,000 years) allows for interpreting fire trends under novel past climate conditions, refining the understanding of climate thresholds that may alter fire regimes in the future.

Expected Results:

In tundra regions that rarely burn today, recent fires likely are anomalous,
related to unique climate conditions at present. When fires did occur in
the past, a relationship to periods of distinct warm and/or dry conditions
is expected. However, tundra burning also is vegetation limited, with
forest-tundra more flammable than shrub-dominated tundra, which in
turn should be more flammable than grass- and sedge-dominated tundra.
Thus, these different vegetation types should have different climatic
thresholds to increased burning.

Potential to Further Environmental/Human Health Protection

This research directly impacts Arctic residents who rely on the natural
resources in the tundra for survival. For example, these data are important
for conservation practices in Alaska, including the design and
implementation of fire suppression strategies. Moreover, understanding
the effects of ongoing climate change on tundra ecosystems will provide
information on empirical climate-fire-vegetation relationships necessary
to anticipate changes under future climate scenarios.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.